603-632 's are the OTA channels at this point - though that will clearly expand out to at least 644 and 666, lol. Paxson has to love that designation.
Discovery HD Theater was part of freebie HDTV with Digital Box so they put that at 690.
They put premium subscription HBO-HD at 700 and Showtime-HD at 701.
They then decided to build a HD Package they sold for an additional amount ($5 or $6 as I recall) that included:
703 INHD
704 INHD2
705 HDNET
706 HDNET Movies
707 was added for ESPN-HD in the HD Package.
They added TNT-HD at 691, but I believe (though not sure) that it is part of the free HD Package you get with a HD STB, thus the difference in the 600s and 700s. That would seem to be the only reason to put it at 691.
When Universal HD was put on for several weeks, it appeared in the Sports Tier of 540 which obviously was strange - except for the US Open Coverage.
HD PPV Movies is located at 750.
If I am not mistake the Orlando Stations are in the 1000 range.
Of course, all these channels are virtual anyway, so it has no meaning in terms of frequency.